In the growth of amorphous and crystalline semiconductor materials, it is frequently desirable to employ a sealed ampoule in order to protect exposed areas of the furnace from any corrosive vapors evolved and/or to prevent a change in the composition of the semiconductor charge due to preferential vaporization of one or more of its components and/or to prevent contamination of the semiconductor charge by the external environment. Representative semiconductor materials are doped and undoped germanium (Ge); III-V's such as GaAs, InP, and GaAlAs; and II-VI's such as PbTe, PbSnTe, HgCdTe, and GeTe. Semiconductors of these sorts are commonly processed in sealed ampoules by the Bridgman, quench-anneal, or vapor crystal growth process. A growth ampoule having the desired features for use in these processes, and particularly for the growth of lead-tin-telluride and and germanium doped with gallium, has been constructed for use with the present invention from fused quartz. The unique seal and process for sealing these charged fused quartz ampoules forms the subject matter of the present invention.
In summary, the current needs of semi-conductor developers are to be able to produce precisely controlled compositions, free of unknown contaminations, sealed in vacuum containers, which are structurally robust as related to shock or pressure, and which can be subjected to wide temperature ranges without losing structural integrity nor causing composition contamination. To meet these needs, it is necessary to simultaneously control distortion of the container ampoule, control the precise amount of "trapped" atmosphere within the ampoule, control of any contaminant emission during the assembly, and control of outgassing during the annealing cycle. In addition, it is required that the volume of the ampoule be variable, subject to the above constraint of precise repeatability, for the purpose of allowing changes in the semi-conductor charge. Further, no portion of the completed ampoule can be allowed to produce internal contaminants due to vaporization or otherwise during the high temperature, low pressure semi-conductor growth cycles.
It is therefore an object of the present invention to provide a novel process for sealing charged semiconductor growth ampoules.
Another object of the present invention is a process for sealing evacuated containers while maintaining the vacuum therein.
A further object of the present invention is a process for sealing fused quartz ampoules with a quartz plug.
An additional object of the present invention is to provide a sealed charged fused quartz ampoule for use in growing semiconductor crystals.
Another object of the present invention is to provide an apparatus for precision sealing of an ampoule while maintaining a vacuum in the ampoule.
An additional object of the present invention is an apparatus for precision sealing of a fused quartz ampoule.